The present invention relates to a multiaxial connection osteosynthesis system, in particular for the spine.
In the context of surgery on the vertebral column, and in particular when using a posterior approach route, the surgeon is often confronted with the problems of misalignment of the anchor members and interference between anchor members on two adjacent vertebrae. This problem increases the operating time or prevents the surgeon from carrying out the desired procedure under the best possible conditions. The cause of this problem is that the coupling member located between the member connecting the various vertebrae and the anchor member implanted in the vertebra is rigidly connected to the anchor member.
Reference WO 97/02786 discloses a multiaxial connection between the members. The anchor member has a hemispherical head. The coupling member includes, in addition to means for receiving the member connecting the various vertebrae together, a split chamber in its bottom part adapted to receive the hemispherical head. The external surface of the coupling member includes a cone that is flared toward the bottom end. A clamping collar can be threaded over the top portion of the coupling member to bear on the conical portion. Before tightening, the coupling member is free to rotate relative to the anchor member. Locking in position is effected when tightening the member connecting the vertebrae together. The member bears on the clamping collar, while at the same time closes the receiving chamber on the hemispherical head of the anchor member.
The complexity of the positional locking mechanism, because of its large number of components, obliges the surgeon to carry out supplementary manipulations, and consequently increases the operating time.
An object of the present invention is to provide a multiaxial connecting device that is simple to use and requires only a small number of operations to complete assembly.